So far as I'm aware, Ken Brooke never claimed credit for coming up with the Baby Gag. His marketed version may well have been the first, and was certainly the one through which it became so popular. But, the name of the actual inventor seems to be lost.

David Acer wrote:I realize this isn't what you mean, but it's the kind of joke stand-up comedians hate magicians for because it doesn't require any investment on the part of the teller.

And magicians hate comedians because they don't have to buy expensive props, don't know any cool moves with a deck of cards, and don't know how 3-fly is done. All they have to do is have a personality, a point of view, and something to say.

I do not believe that Brooke created the original gag. I first saw it as a B&W photo of a generic caucasian baby back at least as far as the early 60's. Brooke added the idea of doing it with a cartoon of a baby, first with the African-American baby on the back, then later opening it to show and Asian baby and one that had more of a reddish tint to it's skin, which could be referred to as an Indian babay.

Hi Guys, I was born in the north of England in a town called Dewsbury in Yorkshire. The local society was called the Mystic 7 which I wasn't allowed to join until I was 16 but I did go and see their Annual Shows or "Night of Magic " as it was usually called. I remember the Compere [M.C.] one year around 1956/7 doing the Baby Gag with a photograph, he said he'd invented it. His name was Cyro billed as the Clown Quince Of Magic his real name was Cyril Brighton and I think he came from the neigbouring town of Wakefield which is also the birthlace of Mystina .She would be too young to remember him but her Father the late great and wonderfully funny Georgie Powell certainly would have. Cyro used to write a monthly column for the Gen back then so if anyone has access to the file he may even have mentioned the gag. He also wrote for the Max Andrews Magic magazine 1954-56 I think with a series called Cyro's Pearls.
I agree with Marc DeSouza that Ken was probably the first to do it with a cartoon and add the African-American Baby to the rear of the card.
Hope this helps and someone can find a reference
Steve Walker

Further to my posting above I located the original instructions that came with the effect which Ken called "Perk Up With Perky" He refers to it being a twist on a very old gag by Ken Perks of Cardiff [Wales]. It is possible that Ken saw the original gag as done by Cyro [who incidently complained about others "knocking it off"]
Remember around the early 1950's Ken would still have been in or around Bradford [Veroni House of Magic] which is only 12 or so miles from Wakefield.
Steve Walker

Just after posting the above i received this from well known UK Comedy magician and old friend Terry Herbert.
"I am afraid I have to correct you regarding the Baby Gag. You probably did not know it but I originated the Black Baby Gag on the reverse side of the White Baby Picture. This was the only thing that Ken Brooke and I fell out about although we made it up afterwards because I was Ken's greatest fan and he was my mentor.
It was in 1966 that I had a photographer make me up a photograph with a White Baby on one side and a Black Baby on the other and I still have the original picture. This was because I used to do the Baby Gag with just the White Baby when somebody actually did call out Nat King Cole so I covered it by saying 'This was him when he was white' which was weak but it got me out of trouble.
So then I came up with the idea of having one on each side, and I remember very clearly performing it at an IBM Convention in the sixties(reported in The Budget) and had Paul Graham call out Sammy Davies Junior knowing full well that all the magicians knew the standard Baby Gag. I acted all embarrassed finally producing the Black Baby and it went a storm. It was some years later that Ken put it on the market advertising it but not saying what the gag was. He claimed that Ken Perks gave him the idea and I am sure he did but where he got it from is open to question
It is water under the bridge now and the only people who knew the facts were Ali Bongo & Vic Pinto but like many gags and tricks, the originations get lost and forgotten over the years but I just felt I should put you in the picture.Regards Terry."

To support Terry Herbert, I found this mention in an article on the British Ring Convention in the THE WORLD'S FAIR dated Saturday, September 23, 1967 "Then came Terry Herbert, with added sidewhiskers, and amusing gags: a Glass of Beer production and vanish, the " Baby Photo " leg-pull, an " Up the Garden Path" type of Borrowed Ring routine culminating in a Davenport Crystal Casket, and introducing pretty Averil to have her lovely neck placed in peril from the fearsome Diamond Guillotine "